Bad moon rising

By Perry Vlahos

Most of us have watched a sunrise. Few have seen a moon rise. Even fewer have witnessed a bad moon rising such as will be able to be seen at sunset on Tuesday, April 15.

Take a deck chair or banana lounge and find a spot with a clear view to the east, so you can see right down to the distant hills or horizon. However, be ready for a shock, for there will be something wrong with our natural satellite. By all rights, we should be expecting a dazzling full moon to come over the horizon and bathe all in its sparkling cool light. It may take a little time to clear the hills or the horizon, but when it does, you will be in no doubt that this is not the moon you were expecting.

Illustration: Perry Vlahos

Many renowned authors over the years have written about our celestial neighbour in glowing romantic terms. This is not one of those. It is a dark, sinister moon, perhaps best captured in words from the Bible, Shakespeare and John Fogarty, of Creedence Clearwater Revival.

The Bard's narrative in the garden scene of Romeo and Juliet may have nailed it as being ''sick and pale with grief''. Shakespeare could have seen such a moon in his lifetime.

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Many faces: This combination photo shows the moon as it undergoes a total lunar eclipse.

In the popular song written by Fogarty, the lyrics are imbedded with ominous premonitions of a ''bad moon rising'' as a menacing warning.

He sings of ''trouble on the way'', along with ''rage and ruin'' followed by a final plea from the singer as soothsayer to not go out tonight with such impending peril on the rise.

The biblical tale is of Salome and John the Baptist, set against a backdrop of a ''blood-red moon''. For those unfamiliar with the story, young and nubile Salome dances for Herod. He is intoxicated by her performance to such a degree, he will grant her anything. Her mother persuades her to ask for the head of John the Baptist. A blood-red moon rises in the sky to fulfil a prophecy with dire consequences.

The event taking place in our sky next Tuesday is the only natural phenomenon that could explain and inspire these literary references - a total lunar eclipse.

A friend of mine wanted to produce Oscar Wilde's play of Salome outdoors, alfresco style, during the night of a total lunar eclipse some years ago. The idea was to feature lighting and special effects provided by the universe. It would have been a stunning sight, but sadly it did not come to pass.

A total eclipse of the moon is not so special in itself, but what is remarkable this time is that the moon will rise over the eastern horizon already immersed in the full darkness of Earth's shadow.

This does not occur with any frequency and I cannot recall seeing a recent lunar eclipse that exhibited this phenomenon. As the evening progresses, however, our luminous natural satellite will regain the lustre associated with a full moon and by about 8.30pm it will resemble its old normal self.

For an eclipse of the moon to occur, the celestial geometry must be just right and the three protagonists in this natural drama, sun, Earth and moon, must line up perfectly. Astronomers call this ''syzygy'' - keep it in mind for a big score in your next Scrabble game. The arrangement of the sun at one end, Earth in the middle and the moon at the far end allows Earth to cast a long shadow into space. The moon's orbit first carries it through Earth's lighter shadow, called the penumbra, before passing into the umbra, or deepest shadow, and remains fully eclipsed for about one hour and 18 minutes.

For observers in the eastern states, moonrise occurs about halfway through this phase. The moon will emerge from the umbra at about 7.30pm and will take another hour or so to regain its customary brilliance.

The word ''eclipse'' comes from the Greek word ''to hide'' or ''to vanish''. Although the eclipse had been observed by many cultures throughout history, the Greeks were the first to write about it scientifically, forming an explanation without attributing it to supernatural forces.

By observing eclipses carefully, they deduced that the moon did not have any of its own natural light, but rather was shining by virtue of the sun's reflected light. This was established by noting its light was extinguished when Earth's shadow fell on it. They also deduced that Earth was spherical, by watching Earth's shadow traverse the surface of the moon and noting that it was curved. References to ''blood red'' moons are real, but the accompanying superstitious prophecies of impending calamity are all highly fictitious.

The key to understanding this mystery is that even through the darkest part of the eclipse, some of the sun's rays reach the moon, bent around Earth by its atmosphere. Sunlight contains all the colours of the spectrum, but only red light can penetrate through the dust and gas in our atmosphere to reach the moon.

If only a small amount of dust is present in our gaseous envelope, then more than just the red light can get through, giving us a grey or yellow-hued moon. More dust gives it a tobacco colour and the range continues to blood red, when a great amount of dust is mixed with the air.

The colour of the moon during an eclipse, then, is no more than a report card on the state of our atmosphere, and unlike Fogarty, I urge you to go out and get a front-row seat for this unique natural spectacle.